Problem: Simplify the following expression: $r = \dfrac{7x + 9}{3x - 8} \div 5$
Dividing by a number is the same as multiplying by its inverse. $r = \dfrac{7x + 9}{3x - 8} \times \dfrac{1}{5}$ When multiplying fractions, we multiply the numerators and the denominators. $r = \dfrac{(7x + 9) \times 1} {(3x - 8) \times 5}$ $r = \dfrac{7x + 9}{15x - 40}$